The study reported in this Monograph of the effects of
early supplementary feeding on cognition included two data collection periods: a
longitudinal investigation spanning the years 1969- 1977 and a cross-sectional
follow-up carried out in 1988-1989. The study was conducted in four rural
villages in Guatemala and compared the differential effects of exposure in
childhood (0-7 years) to an Atole supplement (11.5 g of protein; 163 kcal) or a
Fresco supplement (59 kcal) on performance on a battery of psychoeducational and
information-processing tests in adolescence and young adulthood (11-24 years).
In this report, particular attention is given to a cohort of subjects who were
exposed to the supplement prenatally and during at least the first 2 years of
postnatal life. Data on this subsample are contrasted with those on a cohort of
subjects who received the supplement only after 24 months of life. The
Monograph also reports results from an analysis of the supplementation
effects in infancy and early childhood.

Consistent differences between groups on the psychoeducational
tests were observed. Adolescents from Atole villages scored significantly higher
on tests of knowledge, numeracy, reading, and vocabulary than Fresco subjects.
Atole was also associated with a faster reaction time in information-processing
tasks. Significant interactions helped identify two groups who benefited more
from the Atole treatment: those at the lowest levels of socioeconomic status and
those who attained the highest levels of primary schooling. The consistent
differences in test performance established in the follow-up assessment contrast
sharply with the few and less pronounced between-group differences observed in
the infancy and preschool periods.

After close scrutiny of alternative hypotheses, it is concluded
that nutritional differences provide the strongest explanation for the test
performance differences observed in the follow-up between the subjects exposed
to the Atole and those exposed to the Fresco
supplement.